This invention relates to an improved method for producing a glare-reducing lithium-silicate coating on a surface.
In U.S. Pat. No. 3,635,751 to G. E. Long et al., there is described a glare-reducing coating for a glass surface, said coating having a rough surface and composed of a lithium-silicate material. That coating may be prepared by applying to a warm (30.degree. to 100.degree.C) glass surface a coating of an aqueous solution containing a lithium-stabilized silica sol, drying the coating, and then baking the dry coating to about 150.degree. to 450.degree.C. Submicron-sized carbon particles may be included in the coating to provide a light-attenuating characteristic to the coating.
It has been observed that glare-reducing lithium-silicate coatings on cathode-ray-tube faceplates develop objectionable haze or "bloom" upon standing or storage, as in a warehouse, at normal ambient humidities and temperatures. The haze is objectionable esthetically and also it reduces the brightness and color fidelity of the transmitted image. A similar haze is observed for sodium and potassium silicate coatings that have been baked at temperatures of about 400.degree. to 500.degree.C.
It has also been observed that some glare-reducing lithium-silicate coatings which contain also light-attenuating particles therein transmit an image which appears to have a brownish or other tint. Such tint reduces the color fidelity of the video image and is frequently distracting to the viewer.